How to increase number of visible hairs in particle edit mode?
could it be that you have children visualized (default enabled in quick fur)?

this is with children, as in quick fur, and they are visible only in object/render mode (I think there's no way to visualize children during editmode). You could convert from the modifier panel to a real mesh, perhaps, so that children become "real", but you'll loose particle behaviour...



which in particle edit mode becomes



and this is the same mesh without children, in object and edit mode